Four of the last eight elected mayors who preceded Bob Filner either left office amid allegations of graft or admitted later wrongdoing.

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San Diego Mayor Bob Filner is facing demands that he resign seven months into his term.

He's only been in office for seven months, and combative San Diego Mayor Bob Filner is already fighting to keep his job, facing allegations of sexual harassment and bringing unwelcome attention to a city that has struggled for years with political corruption, fiscal mismanagement and civic strife.

Four of the last eight elected mayors who preceded Filner either left office amid allegations of graft or admitted later wrongdoing.

And now Filner, a former congressman elected last November on a pledge to reform City Hall, finds himself the target of withering criticism from former supporters demanding that he step down.

Filner initially countered that there were "no allegations to respond to." But on Thursday afternoon, he released a pre-recorded statement in which he apologized to the city and promised to "change my behavior."

"As someone who has spent a lifetime fighting for equality for all people, I am embarrassed to admit that I have failed to fully respect the women who work for me and with me, and that at times I have intimidated them," Filner said. "I am also humbled to admit that I need help."

The allegations are the latest flashpoint of a tumultuous term that has included claims of improper dealings with a developer, a secret trip to France and questions about his treatment of staff members and political opponents.

Collectively, the grievances raise the question: Why does San Diego City Hall suffer so much trouble?

The answer is difficult to determine.

One possible explanation offered by political observers is that good government depends on robust civic engagement, and San Diego needs more of it.

"The only hypothesis I could come up with is that compared to other big cities, people tend not to pay attention to San Diego politics," said Brian Adams, an associate professor of political science at San Diego State University. "The mayor and council get a lot less attention than those of Los Angeles or New York City or San Francisco. And because of that, politicians may think they can get away with more. It may be the lack of public attention, reducing the amount of oversight."

He added: "I'd love to see the percentage of San Diegans who can actually name the mayor."

Steven Erie, a historian and political scholar at the University of California at San Diego, wrote a book on the city's municipal problems, titled "Paradise Plundered: Fiscal Crisis and Governance Failures in San Diego." He is blunt in his assessment of the city as politically "amateurish," a relatively young town that hasn't really grown up.

He blames a set of unique circumstances.

First, Erie said, San Diego is a military town, and the culture of unquestioned authority bleeds into civilian life.

For much of the city's recent political history, City Hall had friendly ties with the business community, Erie said. Critics blame that coziness in part for the city's mishandling of its pension funds that led to a lengthy financial crisis. Filner happens to come from outside that power structure, but that has not inoculated him from trouble.

Second, because of the Navy, and San Diego's physical beauty, the city attracts a lot of people from other parts of the country. These transplants are not as invested in local politics, Erie said. Many are more concerned that the weather stays nice.

"People just are not involved," he said. "They don't care."

The result, Erie argues, is a string of embattled or ineffective mayors, broken by one or two good ones.

The list starts with Mayor Frank E. Curran, elected in 1963 and defeated in 1971 while under indictment for allegedly taking bribes. He ended up being acquitted. He was replaced by Pete Wilson, the future governor, who is widely considered the city's best mayor of recent memory.

After Wilson came Roger Hedgecock, who lasted two years before he was convicted on charges of illegal campaign fundraising. The California Supreme Court later threw out most of the convictions. He ended up pleading guilty to a single felony that was later reduced to a misdemeanor, and finally expunged from his record.

Hedgecock was replaced by Maureen O'Connor, the city's first female mayor, who served from 1986 to 1992. She did not get into much legal trouble during her time in office; her shame came later. O'Connor pleaded guilty this year to charges that she misappropriated more than $2 million from her late husband's charitable foundation to finance a nearly decade-long gambling habit.

The next troubled mayoralty was of Dick Murphy, elected in 2000. His administration was overwhelmed by allegations of financial mismanagement -- stemming from a $1.4 billion pension deficit -- securities fraud and corruption. He stepped down in 2005.

His interim replacement was city councilman Michael Zucchet, who served just three days before he stepped down after being convicted in a campaign corruption case. A judge ended up throwing out those convictions, and a new trial resulted in their dismissal.

Around that time, a local congressman, Rep. Randy "Duke" Cunningham, pleaded guilty to accepting more than $2 million in bribes. That scandal did not touch City Hall, but it didn't help San Diego's image.

Jerry Sanders was elected mayor in 2005, and he served until 2012. He is largely credited with steadying the city's fiscal outlook.

Sanders was succeeded by Filner, who took office in December 2012.

And now he, too, is facing demands that he quit.

So far, he has shown no signs of giving in.

Even his public apology on Thursday showed no hint of a resignation.

“You have every right to be disappointed in me," Filner said. "I only ask that you give me an opportunity to prove I am capable of change, so that the vision I have for our city’s future can be realized.”